The presidents of Venezuela and Ecuador have ordered troops to their countries' respective borders with Colombia, after Colombian forces bombed a rebel camp in Ecuador's territory. VOA's Michael Bowman reports from Washington, the surge in tensions are the latest chapter in a period of frosty relations between Colombia's U.S.-backed leader and Venezuela socialist-firebrand president.

Colombia and Venezuela both trace the origins of their nationhood to the independence movement led by South American revolutionary hero Simon Bolivar in the early 1800s. Despite historical ties, relations between the two countries have often been contentious, marked by border disputes, resentment over migration between the two countries, and periodic diplomatic squabbles.

Those tensions have escalated since 2002, when Colombians elected Alvaro Uribe, a firm ally of the United States, as president. Ideologically, Mr. Uribe is the polar opposite of Venezuela's self-proclaimed socialist leader, Hugo Chavez. The two have traded bitter accusations and pointed insults, often centering around Colombia's efforts to eradicate leftist guerrillas known as the Revolutionary Armed Forces of Colombia, or FARC, and Mr. Chavez' efforts to act as an intermediary in the conflict.

Riordan Roett directs Western Hemisphere Studies at Johns Hopkins University's School of Advanced International Studies.

"There have been constant tensions along the border, accusations that at times the 'Chavistas' [Chavez forces)] support the FARC, accusations by the Venezuelans that the rightwing paramilitaries operating in Colombia cross over into Venezuela," said Riordan Roett. "It is a very difficult border to police."

In November, Mr. Uribe terminated the Venezuelan leader's role as mediator in efforts to win the release of FARC held hostages, saying Mr. Chavez was not an impartial broker.

But if relations between Caracas and Bogota continue to deteriorate, ties between Caracas and Quito have flourished since Ecuador elected leftist Rafael Correa as president. As a result, when Colombia bombed a FARC rebel camp less than two kilometers across the Colombia-Ecuador border days ago, President Chavez was quick to jump to Ecuador's defense.

The Venezuelan leader said he is putting his country on alert, and that Venezuela will support Ecuador in any way possible.

Colombia has expressed regret over the cross-border military strike, but characterized it as a move dictated by necessity. Foreign Minister Fernando Araujo:

The minister says Colombia wants to present apologies to Ecuador for the action it was forced to take on the border regarding the access of Colombian armed forces into Ecuador's territory.

Western Hemisphere studies professor Riordan Roett says it has become clear that FARC rebels are operating freely outside Colombia, encountering little if any resistance from neighboring governments.

"The Ecuadorians have looked the other way when leadership from the FARC has entered into Ecuador," he said. "They [the FARC] have done so peacefully, so there has probably been an understanding between the FARC leadership and the Ecuadorean military: no FARC activity in Ecuador in exchange for a safe haven."

In recent decades, many Latin American nations have managed to end guerrilla insurgencies through negotiation or military victory. Not so in Colombia. Once again, Riordan Roett:

"The FARC have been able to maintain themselves through kidnappings and through very close ties with the drug mafia," said Roett. "They are a very powerful, well-armed force that appears at times to be as powerful as the Colombian army themselves. And so there really has been a stand-off. I think it is working in Uribe's favor these five or six years: the FARC have diminished in size; they control less territory than they did [before Uribe came to power]. But Colombia is a big country where the government has rarely penetrated large parts of the hinterlands, where the FARC and the paramilitaries have been able to operate relatively freely."

Colombia has long accused Venezuela's Hugo Chavez of covertly backing the FARC. Monday, Colombian authorities stated that documents and computer records recovered from the recently-bombed rebel camp in Ecuador detail financial transactions between Mr. Chavez and the FARC. In the past, the Venezuelan leader has dismissed Colombia's allegations of ties to guerillas as lies spewing from a U.S. puppet regime.

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